1. Field of the Invention
The present invention relates to a contact type color image sensor which is enabled to sense a color image by forming color filtering layer on a light receiving area of a contact type image sensor and a method of fabricating the same.
2. Description of the Prior Art
A photoelectric converting element of a sandwich type which uses as its photoconductive layer an amorphous semiconductor thin film made of such material as hydrogenated amorphous silicon (a-si:H), exhibits an excellent photoelectric conversion characteristic, is simple in structure and is easily made to provide a large light receiving area. For these reasons, such elements have found wide applications to original document readers which comprises a contact type image sensor having the same sensor section width as that of original documents. That is, the contact type image sensor is a large-area device not requiring any reduction optical system when reading documents.
For example, as above mentioned, a photoelectric converting element which uses as its photoconductive layer a hydrogenated amorphous silicon layer and which is sandwiched by a metallic electrode and a light permeable electrode exhibits an excellent sensitivity of spectrum in wide range of visible light wave-length from 400 mn to 650 nm, so that a contact type image sensor which reads original color documents by forming predetermined color filters on each of many photoelectric converting elements arranged on a transversely elongated substrate has been proposed.
That is, as shown in FIG. 4 and FIG. 5 (FIG. 5 is a cross-sectional view taken along line A--A in FIG. 4) a contact type color image sensor comprises many photoelectric converting elements in which a photoelectric converting layer 3 made of a hydrogenated amorphous silicon layer is sandwiched by a light permeable electrode 4 made of an indium tin oxide (ITO) thin film and a plurality of metallic electrodes 2 made of a chrome (Cr) thin film separately arranged in a row on an insulating ceramic substrate 1, and on which red transmissive filter 5, green transmissive filter 6 and blue transmissive filter 7 are allocated in sequence corresponding to each of metallic electrodes respectively by such as an vacuum evaporation process.
However, there have been practical difficulties experienced in making it, because formation of a filtering layer by an evaporated process at temperature of over 400.degree. C. results in defects in a hydrogenated amorphous silicon layer.